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Derek Taylor 🐧

4 years ago

Derek Taylor 🐧
4 years ago

Stop Pretending "/bin/sh" Is A Real Shell #shorts

youtube.com/watch?v=xQ4KJF-6Ag…

in reply to Derek Taylor 🐧

Nanook

in reply to Derek Taylor 🐧 4 years ago

It's the original shell but these days usually a symlink to bash or dash.

in reply to Derek Taylor 🐧

Kenneth Gardner ( pub)

in reply to Derek Taylor 🐧 4 years ago

This video is hilarious, from the dumb style to the deliberately bad misinformation.

in reply to Derek Taylor 🐧

rob

in reply to Derek Taylor 🐧 4 years ago

I'm pretty sure it's a mistake to symlink /bin/sh to a non-POSIX compliment shell.

in reply to rob

Nanook

in reply to rob 4 years ago

@rob @Derek Taylor 🐧 Both dash and bash adjust their behaviors when called as /bin/sh.

in reply to Nanook

rob

in reply to Nanook 4 years ago

My understanding is that only commands that are POSIX-compliant will work when either of those shells are called with /bin/sh.

in reply to Derek Taylor 🐧

Zeth

in reply to Derek Taylor 🐧 4 years ago

Huh, and here I thought that /bin/sh WAS an actual POSIX-compliant shell...but if it's just a symlink to whatever the hell you have for shell then what exactly is the point of all that nonsense?

in reply to Zeth

Nanook

in reply to Zeth 4 years ago

@Zeth @Derek Taylor 🐧 No but for systems with bash or dash it is, other shells like csh and tcsh can not pretend to be /bin/sh.

in reply to Nanook

not to mention the fact that POSIX standard is lowest common denominator across multiple systems, which seems to me like fundamentally flawed design - because rather than improving on the shortcomings, you instead limit the potential of more advanced implementations...

in reply to Zeth

Zeth

in reply to Zeth 4 years ago

perhaps I'm not seeing the full picture though.

in reply to Zeth

Nanook

in reply to Zeth 4 years ago

@Zeth @Derek Taylor 🐧 No, you can write shell scripts #!/bin/bash to take full advantage of bash, or #!/bin/tcsh to use terrible cshell, or #!/bin/perl to use perl, etc.

in reply to Derek Taylor 🐧

dalz

in reply to Derek Taylor 🐧 4 years ago

/bin/sh is a *real* shell with a *real* specification and multiple, compatibile *real* implementations. You should always try to write POSIX compliant scripts if you don't have good reasons to do otherwise. Also, how could /bin/sh be the user's default shell? You can have multiple users with different login shells on your system, you know?

in reply to dalz

Nanook

in reply to dalz 4 years ago

@dalz @Derek Taylor 🐧 Yes but the #!/bin/sh tells the operating system to use /bin/sh to execute that code REGARDLESS of what the users login shell is.